Loop type antenna systems have been known and utilized effectively for many years. A loop antenna has many applications due to its relatively small size and directivity. Additionally, the loop antenna has a very high Q factor and has a narrow bandwidth of approximately 15-20 KHz when used in the high frequency spectrum around 6 MHz. Unlike coaxial type devices, the loop has only one point of resonance and cannot be used with even or odd multiples of a desired operating frequency.
One problem associated with using this type antenna is matching the antenna to the transmitter for which it is to be used. The high Q factor allows the antenna to be tuned only to one very sharp and selective frequency. The typical method of tuning this and other types of antennas to resonance is to continually adjust the dimensions of the antenna as well as its associated matching network while checking the voltage standing wave ratio (VSWR) along the feed line. The VSWR is generally calculated by measuring the power radiated by the transmitter as well as the power which is reflected due to antenna impedance mismatch. The ratio or percentage the forward power to reflected power is the VSWR. Ideally, an VSWR of 1:1 would offer the best performance where the antenna is perfectly matched to the transmitter and no radiated power is reflected back through the feed line. Thus, to achieve the lowest VSWR possible it was necessary to continually adjusting the antenna while measuring the VSWR. This quickly turns into a cumbersome ordeal particularly when the antenna is located some distance from the VSWR measurement point and where only one person is involved.